The invention relates to an apparatus and method for monitoring the service life of adsorption cartridges which desiccate and/or cleanse moist pressurized air of harmful substances, such as carbon oxides, aromatic hydrocarbons, hydrogen sulfide, and the like, and wherein the apparatus includes a timepiece for counting the operating hours.
Filters used in compressed air systems must be periodically serviced. The servicing not only involves the draining of the condensate, which is usually done automatically, but also the changing of the filter cartridges which, after a certain period of operation, i.e., at the end of their service life, have deteriorated to the point of ineffectiveness. The cartridges in question may be those of the desiccant type used exclusively for the removal of moisture from the pressurized air, or they may be cartridges of the cleansing type used for separating harmful substances.
It is of vital importance, especially in the case of high-pressure type compressors used for filling respirator bottles with air, that the adsorption cartridges be replaced in due time, because a deteriorated filter cartridge is not effective in filtering out the harmful substances from the pressurized air. With systems of the known type, replacement of the adsorption cartridge takes place after a certain operating period specified by the manufacturer. In order to be on the safe side, the life of such an adsorption cartridge specified by the manufacturer is determined on the basis of the most unfavorable operating conditions. The disadvantage of this procedure is that in many instances the adsorption cartridges are replaced long before the end of their useful life, because the cartridges have been used under conditions much more favorable than those assumed by the manufacturer in determining the maximum permissible service life. One important factor in determining the useful life of such an adsorption cartridge is the moisture content of the pressurized air being filtered, because the common adsorption materials, preferably activated carbon, after being saturated with moisture, are not effective to separate the aforementioned harmful substances. The same is true of desiccant cartridges which are only effective as long as they are not saturated with moisture.